『Abstract
　A sequential extraction scheme was used to differentiate different P fractions in the interbedded turbiditic/pelagic sediments of the Madeira Abyssal Plain. These fractions were: ‘carbonate-associated + exchangeable phosphate’ (Pex), ‘iron- and aluminum-associated phosphate’ (POH), ‘calcium-associated phosphate/apatite’ (PHCl), ‘organic phosphorus’ (Porg), and ‘remaining phosphorus’ (PR).
　The Pex forms a minor fraction of the total sedimentary phosphorus (Ptot), whereas for most samples PHCl represents near 80％ of the Ptot. The amount of P in most fractions appears to be determined by the composition and provenance of the various turbidites. The relatively high Pex and the moderately high ‘apatite-P’(PHCl) for the sediment of turbidite e (‘organic-rich’ turbidite provenance group) may point to a source area that is possibly upwelling-related. On the other hand, the high PHCl for the sediments of the turbidites b,g,n,o,p corresponds nicely to their ‘volcanic’ and near-coastal provenance area.
　In contrast to this major impact of inherited P, only a small contribution comes from P that is associated to post-depositional re-allocation of Fe (POH). This results in a POH concentration that is slightly higher in the upper post-depositionally oxidized layer of a turbidite than it is in the lower still un-oxidized layer of the same turbidite. In addition, this postdepositional oxidation of the upper layer of a turbidite may also result in enhanced Fe and P levels in the overlying pelagic interval.
　The C/P molar ratio for organic matter in these sediments is much higher than that reported for more recent sediments, and for average marine plankton (1200 versus 500, and 106, respectively), which may be caused by postdepositional differential decomposition of organic matter.』

Introduction
Materials and methods
　Sequential extractions
　Other analytical methods
　　Organic carbon (Corg)
　　NH4Ac pH 8.2
　　NaAc/HAc pH 5
　Statistical methods
Results and discussion
　Exchangeable and carbonate-associated phosphate (Pex)
　Iron- and aluminum-associated phosphate (POH)
　Calcium associated phosphate/apatite (PHCl)
　Remaining phosphorus (PR) and total phosphorus (Psum and Ptot)
　Total phosphorus (Psum and Ptot)
　Organic-phosphorus (Porg)
　P-fractions in MAP sediments as related to their provenance
Conclusions
Acknowledgements
Appendix 1: Some details of the P extraction analytical methods
　1. Total phosphorus (Ptot) [after Aspila et al., 1976]
　2. Exchangeable and carbonate-associated phosphate (Pex)
　3. Iron- and aluminum-associated phosphate (POH)
　4. Calcium-associated phosphate/apatite (PHCl)
Appendix 2: Table A1
　5. Residual phosphate (PR)
　6. Organic phosphorus by extraction (Porg)
　7. Organic phosphorus (Porg) [after Aspila et al., 1976]
References

表1　非連続的に様々な試薬によって乾燥した粉末の人工および天然リン化合物から抽出された正（オルト）リン酸塩の％

抽出剤	１ Ca5(PO4)3OH	2 Ca3(PO4)2	3 Fe-P	4 AlPO4・H2O	5 ノジュール
1N　NH4Cl（pH 7）	3-6	4-6	5-7	4-6	10
0.1N　NaOH	＜1	＜1	99	91	4
0.5N　HCl	100	99	99	100	92
試料中のリンの全量は、0.2〜4 mgの間で変動した；各抽出における試薬は50 ml．（1）ハイドロキシアパタイト、Ca5(PO4)3OH；Riedel-de Haen A.G.による化学製品（純粋）．（2）リン酸カルシウム、Ca3(PO4)2；Merckによる化学製品（純粋）．（3）鉄ハイドロオキシリン酸塩（Ironhydroxyphosphate）、〔Fe-P〕；Hieltjes and Lijklema,1980を参照．（4）アルミニウム正リン酸塩、AlPO4・H2O；BDHによる化学製品（純粋）．（5）コア82PCS16のb-タービダイトの基盤から生じたリン酸塩ノジュール、1゜20.8'N、24゜16.6’Ｗ；本研究の結果、本文参照．Hieltjes and Lijklema (1980)からの表．

表2　本研究で用いた連続抽出法

抽出剤	抽出されたリンの形態
2N　NH4Cl	ゆるく結合（交換可能＋炭酸塩に伴う）〔Pex〕
0.1N　NaOH	FeとAlに伴う〔POH〕
0.5N　HCｌ	Caに伴う、アパタイト〔PHCｌ〕
K2S2O8/H2SO4	残り〔PR〕
K2S2O8/H2SO4	全〔Ptot〕